1. Field of the Invention
The present invention relates to an image signal processing apparatus, and more particularly to an editing processing for an image signal.
2. Related Background Art
With recent advancement of digital signal processing techniques, it becomes possible to encode a large amount of digital data such as moving images, still images and audio signals and to record the encoded data in a magnetic recording medium or transmit it over a communication medium. A system for editing image signals under high efficiency coding by using such digital signal processing techniques is being studied.
FIG. 1 is a block diagram showing the structure of such an editing system.
In FIG. 1, reference numeral 401 represents an image signal input terminal, reference numeral 402 represents a process control signal input terminal, reference numeral 403 represents a recording control signal input terminal, reference numeral 404 represents a processing circuit, and reference numeral 405 represents a recording circuit.
The operation of this system will be described.
An image signal input from the image signal input terminal 401 is processed by the processing circuit 404. Generally, in a moving image editing process, processes such as fading and wiping are executed. In accordance with a process control signal input from the process control signal input terminal 402, the processing circuit 404 determines the type of a process, start and end timings of the process. The image signal processed by the processing circuit 404 is supplied to the recording circuit 405 and recorded in a storage medium. In accordance with a record control signal from the record control signal input terminal 403, the recording circuit 405 determines start and end timings of the recording.
In such an editing system, the image signal is transferred on the frame unit basis, whereas the process control signal and record control signal are asynchronously transferred by using a transfer path different from that of the image signal. Therefore, as shown in FIG. 2, the input timing of the process control signal may become different from the timing of each frame of the image signal. Also during the recording process, the input timing of the record control signal may become different from the timing of each frame of the image signal because of a difference between delay times specific to respective systems. In such a case, a proper editing process is impossible.
In order to solve this problem, an operator finely adjusts the output timings of the image signal and each control signal externally from the editing system. However, this timing adjustment requires very sophisticated experiences and is different for each system. Therefore, the manual timing adjustment is very difficult.
It is an object of the present invention to solve the above-described problem.
It is another object of the present invention to realize an editing process which is very easy and excellent.
Under these objects, according to one aspect of the present invention, there is provided a signal processing apparatus comprising: input means for inputting an information signal train including image signals of a plurality of frames and additional signals for controlling a process for the image signals, the additional signal being added to the image signal on a frame unit basis; delay means for delaying an input image signal; processing means for processing the image signal output from the delay means; and control means for controlling a process operation to be executed by the processing means and a delay operation to be executed by the delay means, in accordance with the additional signal.
It is a further object of the present invention to provide an editing process capable of easily processing images on the frame unit basis.
The other objects and features of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.